Hydraulic system, vehicle speed control method and gear shifting method for hydrostatic loader

Abstract

The present invention discloses a hydraulic system, a vehicle speed control method and a shifting method for a hydrostatic loader. The hydraulic system includes a travel hydraulic system, a working hydraulic system and a controller; the travel hydraulic system includes a tire, an engine, a travel pump, a first travel motor, an electro-hydraulic proportional reversing valve, a second travel motor, a gearbox and an accelerator pedal; the working hydraulic system includes a steering cylinder, a bucket cylinder, an arm cylinder, a working pump, a steering wheel and a joystick; the controller is used to collect pressure information of the travel pump and the working pump ports, travel information of the accelerator pedal, gear position information of the gearbox, speed information of the steering wheel and angle information of the joystick, and to control the speed of the engine, the displacement of the first and second travel motors, the displacement of the travel pump and the working pump, the opening of the electro-hydraulic proportional reversing valve and the disengagement of the clutch end of the gearbox; the present invention can realize the control of the vehicle speed of the loader and the high-speed shifting function.

Description

Technical Field

[0001] The invention relates to a hydraulic system, a vehicle speed control method and a gear shifting method for a hydrostatic loader, and belongs to the technical field of hydrostatic loaders. Background Art

[0002] Traditional mechanical transmission loaders control the engine speed through the accelerator pedal, and then control the speed of the drive shaft to achieve vehicle speed control. Existing hydrostatic loaders send the accelerator pedal signal to the controller, and the controller requests the engine speed according to the travel of the accelerator pedal. The loader's vehicle speed and engine speed are both positively correlated. The driver perceives the vehicle speed by identifying changes in engine speed. Under this control mode, the engine load rate is at a high level for a small proportion of the time, and energy loss will increase when the load rate is low.

[0003] In addition, the main working condition of the loader is loading. During the entire loading process, there are situations where the working device needs to move quickly while the driving device moves slowly. Traditional mechanical transmission loaders require the driver to step on the brake pedal to balance the relationship between the two, and the energy utilization rate is not high. Existing hydrostatic loaders require the driver to accurately control the inch pedal, brake pedal and accelerator pedal, relying on precise operation to match the speed of the working device and the driving device, which is difficult to control in actual work.

[0004] In addition, for hydrostatic loaders with gears in the transmission, the gear shifting of the transmission is involved, that is, the disengagement and engagement of the travel motor and the transmission. In existing products, due to the limitation of the friction plate of the transmission clutch, the speed difference between the two ends of the engagement cannot be too high, resulting in a limit on the vehicle speed when the travel motor speed is engaged. Under high-speed conditions, in order to protect the transmission clutch, the vehicle speed will be reduced before engaging the travel motor. Under this condition, the entire change process will take a long time, and the vehicle speed change will be more obvious, affecting work efficiency and driving experience. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a hydraulic system, a vehicle speed control method and a gear shifting method for a hydrostatic loader, which can realize the control of the loader's vehicle speed and high-speed gear shifting, and at the same time, achieve the matching of working speed and walking speed based on the actual needs of different drivers and different working conditions.

[0006] To achieve the above object, the present invention is implemented by adopting the following technical solutions:

[0007] In the first aspect, the present invention provides a hydraulic system for a hydrostatic loader, including a travel hydraulic system, a working hydraulic system and a controller; the travel hydraulic system includes tires and an engine electrically connected to the controller, a travel pump, a first travel motor, an electro-hydraulic proportional reversing valve, a second travel motor, a gearbox and an accelerator pedal; the engine output end is mechanically connected to the travel pump shaft; the travel pump oil outlet is connected to the first travel motor oil inlet and the electro-hydraulic proportional reversing valve oil inlet, the electro-hydraulic proportional reversing valve oil outlet is connected to the second travel motor oil inlet, and the travel pump oil suction port is connected to the first travel motor outlet The oil port is connected to the oil outlet of the second travel motor, and the first travel motor and the second travel motor are respectively connected to the non-clutch end and the clutch end of the gearbox; the output end of the gearbox is connected to the tire; the working hydraulic system includes a steering cylinder, a bucket cylinder, an arm cylinder, and a working pump, a steering wheel, and a control handle electrically connected to the controller; the working pump shaft is mechanically connected to the travel pump shaft, and the working pump oil outlet is respectively connected to the steering cylinder oil inlet, the bucket cylinder oil inlet, and the arm cylinder oil inlet, and the working pump oil suction port is respectively connected to the steering cylinder oil outlet, the bucket cylinder oil outlet, and the arm cylinder oil outlet.

[0008] In a second aspect, the present invention provides a method for controlling the speed of a hydrostatic loader. The method is based on the hydraulic system for the hydrostatic loader described above. The method comprises:

[0009] Obtain the target vehicle speed and calculate the target flow rate of the travel system based on the target vehicle speed;

[0010] Obtain the displacement information of the travel pump and calculate the engine speed range [n1, n2] based on the target flow of the travel system;

[0011] Obtaining a target turning speed and a target movement speed, and calculating a target flow rate of the working system based on the target turning speed and the target movement speed;

[0012] Obtain the displacement information of the working pump and calculate the engine speed range [m3, n4] based on the target flow of the working system;

[0013] Determine the engine's permissible speed range [max(n1, n3), min(n2, n4)] based on the engine's speed range [n1, n2], [n3, n4];

[0014] Obtain the travel pump inlet target pressure P1 and travel pump inlet pressure information P3, and calculate the engine torque range [T1, T2] in combination with the travel pump displacement information;

[0015] Obtain the working pump inlet target pressure P2 and the working pump inlet pressure information P4, and calculate the engine torque range [T3, T4] in combination with the working pump displacement information;

[0016] Determine the allowable torque range of the engine [T1+T3, T2+T4] according to the torque range of the engine [T1, T2], [T3, T4];

[0017] Obtain the engine universal characteristic curve and determine the target engine speed based on the engine's allowable speed range [max(n1, n3), min(n2, n4)] and allowable torque range [T1+T3, T2+T4].

[0018] Calculate the target displacement of the travel pump and the working pump based on the target engine speed and the target flow of the travel system and the working system;

[0019] The vehicle speed is controlled according to the target speed of the engine, the target displacements of the travel pump and the working pump, and the target displacements of the first travel motor and the second travel motor.

[0020] Optionally, obtaining the target vehicle speed includes:

[0021] The gear position information of the transmission and the travel information of the accelerator pedal are obtained, and the target vehicle speed is calculated based on the gear position information and the travel information.

[0022] Optionally, calculating the target flow rate of the traveling system based on the target vehicle speed includes:

[0023] Obtaining the transmission ratio between the tire and the first travel motor, and calculating the target speed of the first travel motor based on the target vehicle speed;

[0024] Obtain the transmission ratio of the gearbox and calculate the target speed of the second travel motor based on the target speed of the first travel motor;

[0025] Obtaining speed and displacement curves of the first travel motor and the second travel motor, and obtaining target displacements of the first travel motor and the second travel motor in combination with target speeds of the first travel motor and the second travel motor;

[0026] Calculating target flow rates of the first travel motor and the second travel motor according to target rotation speeds and target displacements of the first travel motor and the second travel motor;

[0027] The sum of the target flow rates of the first travel motor and the second travel motor is used as the target flow rate of the travel system.

[0028] Optionally, obtaining the target turning speed and the target movement speed includes:

[0029] Obtain steering wheel speed information, steering wheel speed information and steering speed curve, and calculate target steering speed;

[0030] Obtain the angle information of the joystick, the angle information of the joystick and the motion speed curve, and calculate the target motion speed.

[0031] Optionally, the calculating the target flow rate of the working system based on the target turning speed and the target movement speed includes:

[0032] Calculate the target flow rate of the steering cylinder according to the target steering speed;

[0033] Calculate the target flow rates of the bucket cylinder and boom cylinder based on the target motion speed;

[0034] The sum of the target flow rates of the steering cylinder, bucket cylinder, and boom cylinder is taken as the target flow rate of the working system.

[0035] Optionally, obtaining the travel pump outlet target pressure P1 and travel pump outlet pressure information P3 includes:

[0036] Obtain the vehicle speed and travel pump outlet pressure curve, and calculate the travel pump outlet target pressure P1 based on the target vehicle speed;

[0037] Obtain the vehicle speed and working pump port pressure curve, and calculate the working pump port target pressure P2 based on the target vehicle speed.

[0038] Optionally, controlling the vehicle speed according to the target speed of the engine, the target displacements of the travel pump and the working pump, and the target displacements of the first travel motor and the second travel motor includes:

[0039] Assume the change time t, and divide the change time t into the acceleration stage t1, the uniform speed stage t2, and the deceleration stage t3, t=t1+t2+t3;

[0040] Assume that the rate of change of parameter i in the acceleration phase t1 is 0-μ i Increase at a uniform speed, in the uniform speed stage t2 is μ i , in the deceleration stage t3 is μ i -0 decreases evenly, and the parameters i=1, 2, 3, 4, and 5 represent the engine speed, the displacement of the travel pump, the displacement of the working pump, the displacement of the first travel motor, and the displacement of the second travel motor respectively;

[0041] Obtaining engine speed information, displacement information of the travel pump and the working pump, and displacement information of the first travel motor and the second travel motor, and calculating the engine speed difference, the displacement difference of the travel pump and the working pump, and the displacement difference of the first travel motor and the second travel motor based on the target engine speed, the target displacement of the travel pump and the working pump, and the target displacement of the first travel motor and the second travel motor;

[0042] According to the engine speed difference, the displacement difference between the travel pump and the working pump, the displacement difference between the first travel motor and the second travel motor, the change rate μ is calculated in combination with the acceleration stage t1, the uniform speed stage t2, and the deceleration stage t3 i value.

[0043] Optionally, the acceleration and deceleration performance of the vehicle speed control can be adjusted by adjusting one or two of the acceleration phase t1, the constant speed phase t2, and the deceleration phase t3.

[0044] In a third aspect, the present invention provides a high-speed shift control method for a hydrostatic loader. The high-speed shift control method is based on the above-mentioned hydraulic system for a hydrostatic loader. The high-speed shift control method comprises:

[0045] Obtain vehicle speed information, and calculate the speed information of the clutch end of the transmission based on the vehicle speed information;

[0046] The speed information of the clutch end of the gearbox is used as the target speed of the second travel motor;

[0047] Obtaining a speed and displacement curve of the second travel motor, and obtaining a target displacement of the second travel motor in combination with a target speed of the second travel motor;

[0048] The displacement of the second travel motor is adjusted according to the target displacement of the second travel motor, and the flow rate of the second travel motor is controlled as a percentage of the flow rate of the travel system through the electro-hydraulic proportional reversing valve;

[0049] The speed information of the second travel motor is obtained. When the difference between the speed information of the second travel motor and the speed information of the gearbox clutch end is less than the preset speed difference, the gearbox clutch end is adjusted to the engaged state, and the second travel motor and the gearbox are engaged to achieve high-speed shifting.

[0050] Compared with the prior art, the present invention has the following beneficial effects:

[0051] The present invention provides a hydraulic system, a vehicle speed control method and a gear shifting method for a hydrostatic loader. The target speed of the engine under different working conditions is determined by the engine universal characteristic curve, so that the engine load rate is maintained at a high level and fuel utilization is maximized. The walking vehicle speed and the working speed are controlled separately when the walking hydraulic system and the working hydraulic system share the same power source (engine). The driver can freely match the walking and working speeds to adapt to different working conditions. At the same time, the traditional hydrostatic inch pedal is eliminated, so that the driver can complete the control of the entire vehicle by operating the accelerator pedal, thereby enhancing the handling comfort. The invention can adapt to different operating habits and freely adjust the acceleration and deceleration performance according to the actual needs of the driver. The invention can realize gear shifting at high speed and effectively reduce the impact of downshifting. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 1 is a layout diagram of a hydraulic system for a hydrostatic loader provided in accordance with a first embodiment of the present invention;

[0053] Figure 2 This is a flow chart of a vehicle speed control method for a hydrostatic loader provided in a second embodiment of the present invention;

[0054] Figure 3 This is a flow chart of a high-speed shift control method for a hydrostatic loader provided in the third embodiment of the present invention. DETAILED DESCRIPTION

[0055] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0056] Example 1:

[0057] like Figure 1 As shown, an embodiment of the present invention provides a hydraulic system for a hydrostatic loader, including a travel hydraulic system, a working hydraulic system and a controller; the travel hydraulic system includes tires and an engine electrically connected to the controller, a travel pump, a first travel motor, an electro-hydraulic proportional reversing valve, a second travel motor, a gearbox and an accelerator pedal; the controller is used to control the engine speed, the displacement of the first travel motor and the second travel motor, the displacement of the travel pump, the opening of the electro-hydraulic proportional reversing valve, the disengagement of the clutch end of the gearbox, and collect the travel pump port pressure information, the accelerator pedal travel information, and the gear position information of the gearbox; the engine output end is mechanically connected to the travel pump shaft; the travel pump oil outlet is connected to the first travel motor oil inlet and the electro-hydraulic proportional reversing valve oil inlet, and the electro-hydraulic proportional reversing valve oil outlet is connected to the second travel motor oil inlet The oil inlet of the travel motor is connected, the oil suction port of the travel pump is connected to the oil outlet of the first travel motor and the oil outlet of the second travel motor, and the first travel motor and the second travel motor are respectively connected to the clutchless end and the clutch end of the gearbox; the output end of the gearbox is connected to the tire; the working hydraulic system includes a steering cylinder, a bucket cylinder, an arm cylinder, and a working pump, a steering wheel, and a joystick electrically connected to the controller; the controller is used to collect the speed information of the steering wheel, the angle information of the joystick, and the pressure information of the working pump port to control the displacement of the working pump; the working pump shaft is mechanically connected to the travel pump shaft, and the working pump oil outlet is respectively connected to the steering cylinder oil inlet, the bucket cylinder oil inlet, and the boom cylinder oil inlet, and the working pump oil suction port is respectively connected to the steering cylinder oil outlet, the bucket cylinder oil outlet, and the boom cylinder oil outlet.

[0058] Example 2:

[0059] like Figure 2As shown, an embodiment of the present invention provides a method for controlling the speed of a hydrostatic loader. The method is based on the hydraulic system for a hydrostatic loader provided in the first embodiment. The method comprises the following steps:

[0060] S1. Obtain a target vehicle speed, and calculate a target flow rate of the travel system based on the target vehicle speed.

[0061] 1. Obtaining the target vehicle speed includes:

[0062] Obtain the gear position information of the transmission and the travel information of the accelerator pedal, and calculate the target vehicle speed based on the gear position information and the travel information;

[0063] For example, the gearbox has two gears. When the gear information is first gear, the travel information 0-100% corresponds to a vehicle speed of 0-15 km / h; when the gear information is second gear, the travel information 0-100% corresponds to a vehicle speed of 0-30 km / h.

[0064] 2. Calculation of the target flow rate of the travel system based on the target vehicle speed includes:

[0065] (1) Obtaining the transmission ratio between the tire and the first travel motor, and calculating the target speed of the first travel motor in combination with the target vehicle speed;

[0066] (2) obtaining the transmission ratio of the gearbox and calculating the target speed of the second travel motor in combination with the target speed of the first travel motor;

[0067] (3) obtaining the speed and displacement curves of the first travel motor and the second travel motor, and obtaining the target displacements of the first travel motor and the second travel motor in combination with the target speeds of the first travel motor and the second travel motor;

[0068] (4) calculating target flow rates of the first travel motor and the second travel motor according to target rotational speeds and target displacements of the first travel motor and the second travel motor;

[0069] The target flow rate of the first travel motor is the product of the target speed and the target displacement of the first travel motor, and the target flow rate of the second travel motor is the product of the target speed and the target displacement of the second travel motor;

[0070] (5) The sum of the target flow rates of the first travel motor and the second travel motor is used as the target flow rate of the travel system.

[0071] S2. Obtain the displacement information of the travel pump (0-100%) and calculate the engine speed range [n1, n2] based on the target flow of the travel system.

[0072] S3, obtaining a target turning speed and a target movement speed, and calculating a target flow rate of the working system based on the target turning speed and the target movement speed;

[0073] 1. Obtaining target turning speed and target movement speed includes:

[0074] (1) Obtaining steering wheel speed information, steering wheel speed information and steering speed curve, and calculating target steering speed;

[0075] (2) Obtain the angle information of the joystick, the angle information of the joystick and the motion speed curve, and calculate the target motion speed.

[0076] 2. Calculate the target flow of the working system based on the target turning speed and target action speed, including:

[0077] (1) Calculate the target flow rate of the steering cylinder based on the target steering speed;

[0078] (2) Calculate the target flow rates of the bucket cylinder and boom cylinder based on the target motion speed;

[0079] (3) The sum of the target flow rates of the steering cylinder, bucket cylinder, and boom cylinder is taken as the target flow rate of the working system.

[0080] S4. Obtain the displacement information of the working pump (0-100%) and calculate the engine speed range [n3, n4] in combination with the target flow of the working system.

[0081] S5. Determine the allowable engine speed range [max(n1, n3), min(n2, n4)] according to the engine speed ranges [n1, n2] and [n3, n4].

[0082] S6 . Obtain the target pressure P1 and pressure information P3 of the travel pump outlet, and calculate the engine torque range [T1, T2] in combination with the displacement information of the travel pump.

[0083] S7, obtaining the working pump port target pressure P2 and the working pump port pressure information P4, and calculating the engine torque range [T3, T4] in combination with the working pump displacement information;

[0084] 1. Obtaining the target pressure P1 and pressure information P3 of the travel pump outlet includes:

[0085] (1) Obtain the vehicle speed and travel pump outlet pressure curve, and calculate the travel pump outlet target pressure P1 based on the target vehicle speed;

[0086] (2) Obtain the curve of vehicle speed and working pump outlet pressure, and calculate the working pump outlet target pressure P2 based on the target vehicle speed.

[0087] 2. Engine torque: Torque T = (travel pump inlet pressure × travel pump displacement) / 2pi.

[0088] S8. Determine the allowable torque range of the engine [T1+T3, T2+T4] based on the torque ranges of the engine [T1, T2] and [T3, T4].

[0089] S9. Obtain the engine universal characteristic curve and determine the target engine speed based on the engine's allowable speed range [max(n1, n3), min(n2, n4)] and allowable torque range [T1+T3, T2+T4].

[0090] The engine universal characteristic curve is a comprehensive curve diagram of engine speed, torque, power and fuel consumption. According to the allowable speed range and allowable torque range, the engine speed with relatively low fuel consumption can be found on the curve diagram.

[0091] S10. Calculate target displacements of the travel pump and the working pump based on the target engine speed and target flow rates of the travel system and the working system.

[0092] S11 , controlling the vehicle speed according to the target engine speed, the target displacements of the travel pump and the working pump, and the target displacements of the first travel motor and the second travel motor.

[0093] To improve driving comfort, vehicle speed control also includes:

[0094] (1) Assume the change time t, and divide the change time t into the acceleration stage t1, the uniform speed stage t2, and the deceleration stage t3, t = t1 + t2 + t3;

[0095] (2) Assume that the rate of change of parameter i in the acceleration phase t1 is 0-μ i Increase at a uniform speed, in the uniform speed stage t2 is μ i , in the deceleration stage t3 is μ i -0 decreases evenly, and the parameters i=1, 2, 3, 4, and 5 represent the engine speed, the displacement of the travel pump, the displacement of the working pump, the displacement of the first travel motor, and the displacement of the second travel motor respectively;

[0096] (3) obtaining engine speed information, displacement information of the travel pump and the working pump, and displacement information of the first travel motor and the second travel motor, and calculating the engine speed difference, the displacement difference of the travel pump and the working pump, and the displacement difference of the first travel motor and the second travel motor based on the target engine speed, the target displacement of the travel pump and the working pump, and the target displacement of the first travel motor and the second travel motor;

[0097] (4) Based on the engine speed difference, the displacement difference between the travel pump and the working pump, and the displacement difference between the first travel motor and the second travel motor, the change rate μ is calculated in combination with the acceleration stage t1, the uniform speed stage t2, and the deceleration stage t3. i value.

[0098] In order to adapt to the operating habits of different drivers, the acceleration and deceleration performance of the vehicle speed control is adjusted by adjusting one or two of the acceleration stage t1, the constant speed stage t2, and the deceleration stage t3.

[0099] Example 3:

[0100] like Figure 3 As shown, an embodiment of the present invention provides a high-speed shift control method for a hydrostatic loader. The high-speed shift control method is based on the hydraulic system for a hydrostatic loader provided in the first embodiment. The high-speed shift control method includes:

[0101] S1. Obtain vehicle speed information, and calculate the speed information of the clutch end of the transmission based on the vehicle speed information.

[0102] S2. Using the speed information of the transmission clutch end as the target speed of the second travel motor (the transmission clutch end is in a disengaged state at this time).

[0103] S3. Obtain a speed and displacement curve of the second travel motor, and obtain a target displacement of the second travel motor in combination with a target speed of the second travel motor.

[0104] S4. adjusting the displacement of the second travel motor according to the target displacement of the second travel motor, and controlling the flow rate of the second travel motor as a percentage of the flow rate of the travel system through the electro-hydraulic proportional reversing valve;

[0105] Since the clutch end of the gearbox is in a disengaged state, the second travel motor is in a no-load state, and its flow rate is likely to be too large, resulting in excessive speed increase. Therefore, by controlling the opening of the electro-hydraulic proportional reversing valve, the flow rate of the second travel motor is guaranteed to account for a certain percentage of the flow rate of the travel system, thereby stabilizing its flow rate and speed.

[0106] S5. Obtain the speed information of the second travel motor. When the difference between the speed information of the second travel motor and the speed information of the transmission clutch end is less than the preset speed difference, adjust the transmission clutch end to the engaged state, and the second travel motor and the transmission are engaged to achieve high-speed shifting.

[0107] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0108] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0109] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0110] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0111] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for controlling the vehicle speed of a hydrostatic loader, wherein the hydraulic system of the hydrostatic loader includes a travel hydraulic system, a working hydraulic system, and a controller; The travel hydraulic system includes a tire and an engine electrically connected to a controller, a travel pump, a first travel motor, an electro-hydraulic proportional reversing valve, a second travel motor, a gearbox, and an accelerator pedal; the engine output end is mechanically connected to the travel pump shaft; the travel pump oil outlet is connected to the first travel motor oil inlet and the electro-hydraulic proportional reversing valve oil inlet, the electro-hydraulic proportional reversing valve oil outlet is connected to the second travel motor oil inlet, the travel pump oil suction port is connected to the first travel motor oil outlet and the second travel motor oil outlet, the first travel motor and the second travel motor are respectively connected to the clutchless end and the clutch end of the gearbox; the gearbox output end is connected to the tire; The working hydraulic system includes a steering cylinder, a bucket cylinder, a boom cylinder, and a working pump electrically connected to the controller, a steering wheel, and a joystick; the working pump shaft is mechanically connected to the travel pump shaft, the working pump oil outlet is respectively connected to the steering cylinder oil inlet, the bucket cylinder oil inlet, and the boom cylinder oil inlet, and the working pump oil suction port is respectively connected to the steering cylinder oil outlet, the bucket cylinder oil outlet, and the boom cylinder oil outlet; it is characterized in that The vehicle speed control method comprises: Obtain the target vehicle speed and calculate the target flow rate of the travel system based on the target vehicle speed; Obtain the displacement information of the travel pump and calculate the engine speed range based on the target flow of the travel system ; Obtaining a target turning speed and a target movement speed, and calculating a target flow rate of the working system based on the target turning speed and the target movement speed; Obtain the displacement information of the working pump and calculate the engine speed range based on the target flow of the working system ; According to the engine speed range Determine the permissible engine speed range ; Get the target pressure of the travel pump port And travel pump port pressure information , calculate the engine torque range by combining the displacement information of the travel pump ; Get the target pressure of the working pump port And working pump port pressure information , calculate the engine torque range by combining the displacement information of the working pump ; According to the engine's torque range Determine the engine's permissible torque range ; Obtain the engine universal characteristic curve and combine it with the engine's allowable speed range and permissible torque range , determine the target speed of the engine; Calculate the target displacement of the travel pump and the working pump based on the target engine speed and the target flow of the travel system and the working system; The vehicle speed is controlled according to the target speed of the engine, the target displacements of the travel pump and the working pump, and the target displacements of the first travel motor and the second travel motor.

2. The method for controlling the vehicle speed of a hydrostatic loader according to claim 1, wherein: The acquiring of the target vehicle speed includes: The gear position information of the transmission and the travel information of the accelerator pedal are obtained, and the target vehicle speed is calculated based on the gear position information and the travel information.

3. The method for controlling the speed of a hydrostatic loader according to claim 2, wherein: The target flow rate of the traveling system is calculated based on the target vehicle speed, including: Obtaining the transmission ratio between the tire and the first travel motor, and calculating the target speed of the first travel motor based on the target vehicle speed; Obtain the transmission ratio of the gearbox and calculate the target speed of the second travel motor based on the target speed of the first travel motor; Obtaining speed and displacement curves of the first travel motor and the second travel motor, and obtaining target displacements of the first travel motor and the second travel motor in combination with target speeds of the first travel motor and the second travel motor; Calculating target flow rates of the first travel motor and the second travel motor according to target rotation speeds and target displacements of the first travel motor and the second travel motor; The sum of the target flow rates of the first travel motor and the second travel motor is used as the target flow rate of the travel system.

4. The method for controlling the vehicle speed of a hydrostatic loader according to claim 1, wherein: The obtaining of the target turning speed and the target movement speed comprises: Obtain steering wheel speed information, steering wheel speed information and steering speed curve, and calculate target steering speed; Obtain the angle information of the joystick, the angle information of the joystick and the motion speed curve, and calculate the target motion speed.

5. The method for controlling the vehicle speed of a hydrostatic loader according to claim 4, wherein: The target flow rate of the working system is calculated based on the target steering speed and the target action speed, including: Calculate the target flow rate of the steering cylinder according to the target steering speed; Calculate the target flow rates of the bucket cylinder and boom cylinder based on the target motion speed; The sum of the target flow rates of the steering cylinder, bucket cylinder, and boom cylinder is taken as the target flow rate of the working system.

6. The method for controlling the vehicle speed of a hydrostatic loader according to claim 1, wherein: Obtaining the target pressure of the travel pump outlet And travel pump port pressure information include: Obtain the vehicle speed and travel pump outlet pressure curve, and calculate the travel pump outlet target pressure based on the target vehicle speed ; Obtain the vehicle speed and working pump port pressure curve, and calculate the working pump port target pressure based on the target vehicle speed .

7. The method for controlling the vehicle speed of a hydrostatic loader according to claim 1, wherein: The vehicle speed control according to the target speed of the engine, the target displacements of the travel pump and the working pump, and the target displacements of the first travel motor and the second travel motor includes: Set change time , will change the time Divided into acceleration phase , uniform speed stage , deceleration stage , ; Set parameters The rate of change in the acceleration phase 0- Increase at a constant speed, in the constant speed stage for In the deceleration phase for Uniformly reduce, parameters Respectively represent the engine speed, travel pump displacement, working pump displacement, first travel motor displacement, and second travel motor displacement; Obtaining engine speed information, displacement information of the travel pump and the working pump, and displacement information of the first travel motor and the second travel motor, and calculating the engine speed difference, the displacement difference of the travel pump and the working pump, and the displacement difference of the first travel motor and the second travel motor based on the target engine speed, the target displacement of the travel pump and the working pump, and the target displacement of the first travel motor and the second travel motor; According to the engine speed difference, the displacement difference between the travel pump and the working pump, the displacement difference between the first travel motor and the second travel motor, combined with the acceleration stage , uniform speed stage , deceleration stage Calculating the rate of change value.

8. The method for controlling the vehicle speed of a hydrostatic loader according to claim 7, wherein: By adjusting the acceleration phase , uniform speed stage , deceleration stage One or both of the following can be used to adjust the acceleration and deceleration performance of the vehicle speed control.

9. A high-speed shift control method for a hydrostatic loader, wherein the hydraulic system of the hydrostatic loader includes a travel hydraulic system, a working hydraulic system, and a controller; The travel hydraulic system includes a tire and an engine electrically connected to a controller, a travel pump, a first travel motor, an electro-hydraulic proportional reversing valve, a second travel motor, a gearbox, and an accelerator pedal; the engine output end is mechanically connected to the travel pump shaft; the travel pump oil outlet is connected to the first travel motor oil inlet and the electro-hydraulic proportional reversing valve oil inlet, the electro-hydraulic proportional reversing valve oil outlet is connected to the second travel motor oil inlet, the travel pump oil suction port is connected to the first travel motor oil outlet and the second travel motor oil outlet, the first travel motor and the second travel motor are respectively connected to the clutchless end and the clutch end of the gearbox; the gearbox output end is connected to the tire; The working hydraulic system includes a steering cylinder, a bucket cylinder, a boom cylinder, and a working pump electrically connected to the controller, a steering wheel, and a joystick; the working pump shaft is mechanically connected to the travel pump shaft, the working pump oil outlet is respectively connected to the steering cylinder oil inlet, the bucket cylinder oil inlet, and the boom cylinder oil inlet, and the working pump oil suction port is respectively connected to the steering cylinder oil outlet, the bucket cylinder oil outlet, and the boom cylinder oil outlet; it is characterized in that The high-speed shift control method includes: Obtain vehicle speed information, and calculate the speed information of the clutch end of the transmission based on the vehicle speed information; The speed information of the clutch end of the gearbox is used as the target speed of the second travel motor; Obtaining a speed and displacement curve of the second travel motor, and obtaining a target displacement of the second travel motor in combination with a target speed of the second travel motor; The displacement of the second travel motor is adjusted according to the target displacement of the second travel motor, and the flow rate of the second travel motor is controlled as a percentage of the flow rate of the travel system through the electro-hydraulic proportional reversing valve; The speed information of the second travel motor is obtained. When the difference between the speed information of the second travel motor and the speed information of the gearbox clutch end is less than the preset speed difference, the gearbox clutch end is adjusted to the engaged state, and the second travel motor and the gearbox are engaged to achieve high-speed shifting.

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